1. Field of the Invention
The present invention relates to methods for making composites and, particularly, to a method for making a carbon nanotube (CNT) composite.
2. Discussion of Related Art
Carbon nanotubes (CNTs) are novel carbonaceous materials and have received a great deal of interest since the early 1990s. Carbon nanotubes have interesting and potentially useful heat conducting, electrical, and mechanical properties. Due to these and other properties, an important application for CNTs is their use as fillers in composite materials.
A conventional method of making a carbon nanotube composite includes the following steps: (a) providing 0.3 units of multi-wall carbon nanotubes by weight and 10 units of concentrated nitric acid by weight, placing the multi-wall carbon nanotubes into the concentrated nitric acid to form a mixture, agitating the mixture for 20 hours at a temperature of 200° C., removing the concentrated nitric acid from the multi-wall carbon nanotubes with distilled water, and drying the multi-wall carbon nanotubes in a vacuum for 10 hours at a temperature of 90° C.; (b) placing the multi-wall carbon nanotubes into 10 units of oxalyl chloride by weight to form a mixture, agitating the mixture for 10 hours at a temperature of 90° C., and vaporizing the unreactive oxalyl chloride; (c) placing the multi-wall carbon nanotubes into ice to form a mixture, agitating the mixture slowly, dripping 10 units of diaminoethane by weight, and drying the multi-wall carbon nanotubes in a vacuum for 10 hours at a temperature of 100° C.; (d) placing the multi-wall carbon nanotubes into 20 units of ethanol by weight to form a mixture, cleaning the mixture ultrasonically, adding 2 units of epoxide resin by weight into the mixture, agitating the mixture rapidly for 20 minutes, vaporizing the ethanol, heating the mixture to a temperature of 60° C., adding a solidifying agent into the mixture, and dispersing the multi-wall carbon nanotubes uniformly; and (d) placing the mixture into a die, heating the mixture to a temperature of 80° C., solidifying the mixture for 2 hours, heating the mixture to a temperature of 150° C., solidifying the mixture for 2 hours, and finally obtaining the carbon nanotube composite.
However, the above method can lead to some disadvantages. Firstly, in step (c), it is often difficult to uniformly disperse the carbon nanotubes into the mixture, which can result in high costs. Secondly, in step (a), the process of placing the carbon nanotubes into the concentrated nitric acid is liable damage the integrality of the carbon nanotubes.
What is needed, therefore, is to provide a low-cost method for making a carbon nanotube composite without damaging the integrality of the carbon nanotubes.